please help with tax refund problem

I have tried in vain to contact by phone, with no joy. Every year for the last 3, I have done my self-assessment online, it had been validated within a couple of days, but when I ask for a repayment, nothing happens. 48 hours later, my account looks as though I never asked for the refund. So I try again, and the same thing happens. It's not "pending" or anything like that. I haven't been sent for extra security or whatever. It just says it's going to pay me, and then doesn't. My 2022 refund took 18 months, and 2023 took several months. I'm waiting 2 months already on the 2024 refund. I've tried having it sent to multiple bank accounts, and nothing works. Please can someone help in some way? Telling me I have to call isn't any help at all, because I've tried, and all I get is put on hold indefinitely. There is obviously something wrong with my account. How can I get my refund, and how the the account problem be fixed so I don't have to continue doing this every year?

Please can someone respond? I'm not the only one with this problem, by looking at some of these threads

Hi 
We are sorry to hear about your experience and regret any inconvenience caused.
If you would like to file a complaint you can do so here: 
Complain about HMRC

I don't want to complain; I want the refund to be processed and the problem to be fixed! Will a complaint make that happen?

Hi lizmcphil,
I am sorry you are having issues in claiming your repayment.
If still not received then you will need to contact HMRC to review. You can do this by phone or webchat at:
 Self Assessment: general enquiries.
Thank you.

I have been trying for months, but no-one picks up the phone. Please stop sending the same message telling me I have to call.